Method of handling abrasive material



M. A. ROSS.

METHOD OF HANDLSNG ABRASIVE MATERIAL.

APPLICATION FiLED MAY 15. 1920.

gggse, Patented NOV 8 19210 2 SHEETSSHEET 1.

M. A. ROSS. METHOD OF HANDLING ABRASIVE MATERIAL.

APPLICAUQN FILED MAY 15, I920. 1 ,96,866 Paw-6mm N01 8, 1922.0

2 SHEETSSHEET 2.

recited above,

- lar utility UNITED STATES PATENT OFFICE.

GINIA.

T0 PRESSED PRISM PLATE GLASS A CORPORATION OF WEST VIB- HETHOD OFHANDLING ABRA SIVE MATERIAL.

Application filed May 15,

To all whom it may concern:

Be it known that I, MrnoN A. Ross, a citizen of the United States,residing in Chicago, in the county of Cook and State of Ill nois, haveinvented a new and useful Improvement in Methods of Handling AbrasiveMaterial, of which the following is a specification.

This invention relates to a method of handling and grading abrasivematerial in liquid suspension, such assand mixed with water, andapplying the same to a grinding apparatus, the invention has for anobject the provision of a method of handling such material in acontinuous uninterrupted cycle, which will efiect separation of thecoarser particles of the material from the finer particles into severalgrades while the material flows continuously through the system, andpermit individual delivery, at will, of any grade of the separatedmaterial to the grindmg apparatus, without interrupting the continuousflow of the material and without the necessity of regrading previouslygraded material. In addition to the general object the invention has forfurther objects such other improvements and advantages in operation andresults as are found to obtain in the methods or processes hereinafterdescribed or claimed.

The method of the invention is of particufor supplying in propersequence grades of abrasive material to grindin apparatus, such as iscommonly utilize for grinding and finishing plate glass, and the like.For convenience the present description will be confined to thisparticular use of the, invention; it will be understood, however, thatthe invention is capable of other applications; hence the scope of theinventlon is by no means limited to the particular application orspecific use herein described as an illustrative example.

In the accompargying drawings, formmg a part of this speci cation, andshowing, for purposes of exemplification a diagrammatic representationof an apparatus, by which the method of the apparatus may be practised,but without limiting the claimed invention specifically tosuchillustrative instance or instances:

Figure 1 is a plan view of an apparatus Specification of Letters Patent.

Patented NOV. 8, 1921. 1920. Serial No. 381,585.-

utilized in method;

Fig. 2 is a vertical sectional elevation of the apparatus illustrated inFig. 1;

1g. 3 is a vertical sectional elevation taken on the line 3-3 of Fig. l;7

1g. 4 is an enlarged detailed sectional elevation of the bottom of thesump; and

Fig, 5 is an enlarged detailed sectional elevation of the grading tank.

practising the present improved The same characters of referenceindicate the same parts throughout the several views. In its illustratedembodiment and application, the method ofthe present invention isemployed in connection with a grinding apparatus, such as is commonlyutilized for grinding plate glass and like materials. uch grindingapparatus embodies in its construction a horizontal grinding table 11mounted on the vertical spindle 12 which is supported within the pit 13by suitable bearings 14, 15 and is rotated by any preferred driveconnection to impart a rotary movement to the before mentioned table 11.R0- tatable on vertical axes above the table 11 are the usual runners16, 17 there commonly being a pair of such runners to each table. Theserunners are provided with the usual means for maintaining grindingcontact of an abrasive material with the surface of a plate of glasssupported upon the table 11.

For the purpose of grinding the surface of the plate of glass on thetable 11, there is supplied to the table, in proper sequence, abrasivematerial, such as sand, in progressively finer grades, mixed with asufiicient proportion of water to keep the sand constantly in a fluidstate. In the preliminary grinding operation coarse sand is used, but asthe grinding progresses and the surface of the plate glass becomessmoother, finer grades of sand are used in progressively increasingdegrees of fineness until the surface of the table is smooth enough forbeing pol-.

ished. During the grinding operation on the table, more or less of thesand particles suspended in their liquid carrier become more or lessfinely pulverized, while other articles of sand escape the grindingaction.

here is thus maintained, by the centrifugal force developed in the table11 and the runne s 16 and 17, a discharge into the gutter 18 surroundingthe table 11 which discharge is constituted of a mixture of sandparticles of many diflferent grades of fineness and water.

This mixture of variously-ground sand particles and waterjs washed downaround the incline gutter 18 by a constant stream of water supplied fromties into the gutter at the upper end of the incline, as shown in Fig.3, and the mixture of water and sand flowing down the gutterdischargfisi into a connecting gutter 19, which conveys'the mixturetoand discharges it in a pit 20.' Communicating with the pit 20 is theupper end of a sump or well 21, which may extend vertically into theground a considerable distance below the bottom of the pit 20 and may beconveniently formed by driving into the ground a pipe of proper bore,with the upper portion of the pipe projecting somewhatabove the bottomof the pit and provided with a pluralitfy of inlet holes 22, permittingthe mixture 0 sand and water to pass from the pit into the nterior ofthe pipe, but excluding large particles. of foreign matter such as maybe depos1ted in the mixture, during the grinding operation.

Extending downwardly within the sump 21 and supported on its bottom byfeet 23 is a s1- phon tube 24, the lower end of which is open toconstitute an 21, the siphon tube 24 extends vertically beyond the topof a grading tank hereinafter described and the upper open discharge end26 of said siphon tube is bent over andv into a feed spout 27 mountedabove one end of said grading tank. An air tube 28 supplied withcompressed air from any suitable source also extends downwardly withinthe sump 21 and discharges its air into the siphon tube 21 at a point 29located above the inlet 25 of the siphon tube. There is thus provided apump, the action of which is constantly to lift the mixture of sand andwater discharged into the sump 21, from the grinding apparatus, andforce such mixture u wardly through the siphon tube 24 and discharge itinto the feed spout 27.

Discharging from the bottom of the feed spout 27 the mixture of sandparticles of various sizes and water flows into the grading tank 30. Asshown in Figs. 2 and 5, this grading tank 30 is constituted essentiallyof an elongated trough suspended above and located to one side of thetable 11. The interior of the tank 30 is divided into a plurality ofcompartments 31 by transverse bafiies 32 which progressively decrease inheight intheir order of remotness from the feed spout 27 at the inletend of the tank, as shown more particularly in Fig. 5. As the highestbaflie of the series is nearest the inlet end of the tank and the lowestbaflie of the series is nearest the remote end 33 of the a pipe 18 whichemp-' inlet 25. Above the sump tank, and as the intermediate bafliesprogressively decrease in height from the highest to the lowest bathe inthe tank the mixture of sand and water discharged through the feed spout27 overflows over the highest baffiie 32 of the first compartment of thetank into the next: adjacent compartment thereof, and

subsequently overflowing over the bafiie of such next adjacentcompartment ultimately fills each compartment 31 of the tank. The

filling of these compartments 31 takes place in the order of theirproximity to the feed spout 27, each compartment being fed by theoverflow from its neighbor that is located nearer to such feed spout. Inthe first compartment of the tank, which receives the mixture of sandand water directly from the feed spout 27, the coarse particles of sandin the mixture drop out, by reason of their greater specific gravity andin each successive compartment 31 relatively finer particles of sand areprecipitated, as the mixture flows from compartment to compartment untilthe compartment at the remote end of the tank is reached, where thefinest particles graded out are precipitated. During the grading in thetank 30, the overflow, composed of water and very fine particles of sandof no especial value, discharges through an overflow pipe 34 located atthe remote end of the tank and positioned somewhat be low the bafiie 32at the inlet end of that compartment.

While the grading operation is being eflected in the tank 30, the coarseparticles.

of sand which are precipitated in the first compartment 31 of the tankare continuously returned to the grinding table 11, so long as thecoarse grinding operation is maintained on that table. These coarseparticles of sand mixed with a part of the water discharged through thespout 27, pass out through the orifice 35 locatedin the bottom of thefirst compartment ofthe tank into a valve box 36. This valve boxcommunicates with a coarse sand discharge pipe 37 and a return pipe 38,one of which is closed while the other isopen by means of a flap valve39 located in the bottom of the valve box. Assuming that the valve 39 ispositioned to close the return pipe 38 the mixture of coarse sand andwater passes through the coarse sand discharge pipe 37 to the feedtrough 40-which extends to and over the table 11 and is provided at itsdischarge end with. feed holes 41 through which such mixture dischargesonto the table. After performing its work on the table, the mixture ofcoarse sand is again discharged into the gutter 18, thence through thegutter 19 into'the sump, from which it is returned by the pump to thegrading tank 30, the coarse par ticles again separated out in the firstcomgrading compartments beyond the first compartment of the tank. There15 thus accomplished a continuous separatlon of the coarse particles ofmaterial from the mixture and return of the same in a continuous flow tothe grinding apparatus, coupled with a continuous grading out andseparation of the finer particles of sand of various grades which arereserved for the subsequent finer grinding operation on the table, aswill hereinafter appear. In other words the grading of the sand intoseveral grades of fineness is effected while the material flowscontinuously and the coarse particles are separated out of the mixtureand returned for regrinding, Without interruption in the flow of thematerial and without the necessity for returning the entire volume ofmaterial to the grinding apparatus, which would necessitate a regradingof the entire flow throughout the system. As the material flows throughthe apparatus the combined volume of the flow at the discharge pipe 34and the discharge orifice 35 is approximately equivalent to the volumeof the flow through the discharge end of the siphon tube 24. Should itbe desired to discontinue the return of water and sand to the table 11,the flap valve 39 may be operated to close the coarse sand pipe 37 andopen the return pipe 38, this return pipe leading to the sump andpermitting the coarse sand and water to be returned to the sump and pumpback into the grading tank, without any interruption of the flow.Additional sand may be added to the flow from time to time by shovelingsuch sand into the pit 20 at the inlet of the sump. In starting thegrinding operation, it is usual to shovel a quantity of dry sand on thetable 11, the dry sand being discharged into the gutter by centrifugalforce and washed down the gutter by the water flowing from the pipe 18.in the pipe 18 is regulated to a proximately equal the head of flow inthe discharge pipe 34.

After the preliminar coarse grinding operation has been completed on thetable 11, subsequent grinding is effected by the use of successivelyfiner grades of sand which have been graded out in the severalcompartments 31 of the tank located beyond the first compartment. Eachcompartment of the tank is provided with an overflow discharge orifice42 located somewhat below the battle at the discharge side of thecompartment. These orifices 42 respectively communicate with dischargepipes 43 provided with valves 44 and are all leading to a manifold 45which discharges into the pit 20 at the upper end of the sump. Theseveral compartments 31 located beyond the first compartment arefurthermore provided with bottoms, said outlets 46 respectivelydischarging into pipes 47 leading to the feed into the The water head boutlets 46 in their trough 40. The orifice 35 at the bottoms of thefirst compartments and the outlets 46 in the bottoms of the othercompartments are each adapted to be opened and closed by plugs 48operable from the upper end of the tank. Assuming that the coarsegrinding operation on the table has been completed and it is desired touse the next finer grade of sand, the valve 44 of the first compartmentis opened. The flow tube discharges out of the first compartment throughthe outlets 35 and 42 and thence into the manifold 45 and return pi e 38which returns the flow to the sump. n the next compartment the plug 48is operated to open the outlet 46 and the finer sand may then be washedby the introduction of fresh Water into the top of that compartment outof the outlet 46 and into the pipe 47 which carries such mixture offiner sand and water to the table 11. Subsequently the sand and waterdischarged from the table enters the sump along with the materialdischarged through the manifold 45. After the graded sand in the secondcompartment has been exhausted, the graded sand in the third compartmentmay be conducted to the grinding table 11 in like manner. When this isdone the lug 48 is operated to close the outlet 48 in t e bottom of thesecond compartment whereas the plug 48 is operated to open the outlet 46in the bottom of the third compartment. The valve 43 of the firstcompartment may then be closed and the valve 43 of the secondcompartment opened, permitting a recommencement of the grading operationin the second compartment. Obviously, the same operation may be repeatedin all of the compartments of the tank until the very finest sand isexhausted out of the last compartment which is adjacent .to thedischarge pipe 34. While graded sand is eing washed out of anycompartment of the tank regrading may be carried on in all of thepreviously emptied compartments, with the result that the utilization ofthe finer grades of sand does not interrupt the grading operation northe continuous flow of the material.

The method of the invention may be practised in various ways, other thanthe articular embodiment that has been descrlbed for purposes ofillustration, and still be within the scope and subject matter of theclaims hereinafter made.

I claim:

1. The method of applying abrasives to grinding apparatus, whichconsists in con veying the discharged abrasive material mixed with aliquid to a separation operation while the material flows continuouslyfrom the grinding operation, separating such material into differentgrades of fineness, withdrawing the separated grades of such mateterialin any desired sequence independently from the siphon of other grades,concurrently conveying back the discharge from the grinding apparatusand grading such discharge independently of the material being Withdrawnfrom the separation operation, substantially as specified.

2. The method of applying abrasives to grinding apparatus, whichconsists in discharging the abrasive material mixed with a liquid fromthe grinding apparatus, pumping the discharged material to a gradingtank and therein separating the material into different grades offineness, while continuously returning a portion of the separatedmaterial to the pumping operation, substantially as specified 3. Themethod of applying abrasives to grinding apparatus, which consists indischarging the abrasive material mixed with a liquid from the grindingapparatus, pumping the discharged material to a grading tank and thereinseparating the material into different grades of fineness, Withdrawingthe separated grades of material in said tank in any desired sequence,while apparatus, continuously discharging the mlxture of sand and waterfrom the grind ing apparatus, separating the discharged mixture intodifferent grades of fineness,

while the mixture flows continuously, continuously withdrawing thecoarser grading of such material and returning it to the grindingapparatus, while maintaining a continuous flow of discharge from thegrinding apparatus to the separating operation and then withdrawing theseparated grades of such sand in any desired sequence independently ofother grades While concurrently conveying back the discharge from thegrinding apparatus and grading such discharge independently of the sandbeing withdrawn from the separation operation; substantially as$ecified.

M RON A. ROSS.

